What command is used to display disk usage in human-readable format?

The command to display disk usage in a human-readable format is "du -h." The "du" command stands for "disk usage," and when combined with the "-h" option, it presents the sizes in a format that is easier for humans to interpret, such as using KB, MB, and GB instead of just raw byte numbers. This makes it significantly simpler to understand storage requirements at a glance, especially when dealing with large amounts of data.

Using "du" without the "-h" option would display sizes in bytes, which can be less intuitive. Meanwhile, the "df" command is utilized to report file system disk space usage rather than file or directory usage, and it also has its own options for human-readable output, but it serves a different purpose. The other two options, "diskusage" and "space -h," are not standard commands in most Linux distributions, making them incorrect choices for this particular function.